LEDs have recently been used as a light source for a lighting apparatus. This light source is configured into a lighting apparatus by mounting a large number of LED bare chips on a substrate and electrically connecting the LED chips with bonding wires.
In light emitting elements such as LEDs, a rise in the temperature of the element causes decrease in optical output and variation in characteristics and affects the life of the element. Thus, for light emitting devices using solid light emitting elements such as LEDs as a light source, a rise in the temperature of the element needs to be suppressed in order to improve the characteristics of the element such as the life and efficiency thereof.
As a substrate for light emitting devices, a ceramics substrate is conventionally known; the ceramics substrate has an insulation capability, is unlikely to be significantly thermally expanded, and is suited for applications requiring a heat radiation capability and heat resistance and involving supply of a high current as a driving current. Light emitting elements are mounted on the ceramics substrate by being bonded to the substrate with an adhesive of a resin material.
However, in the conventional light emitting device, since the light emitting elements are bonded to the substrate with the adhesive of the resin material, heat generated by the light emitting elements fails to be efficiently conducted to the substrate. This may prevent effective heat radiation. Furthermore, if light emitting elements are mounted on the substrate, the temperatures of: the light emitting elements may be non-uniform, thus varying optical output and emission colors among the individual light emitting elements.